mackenly / fast-nameserver-lookup

Experiments and benchmarking to compare the speed of a Rust-based nameserver lookup to dig

fast-nameserver-lookup

Experiments and benchmarking to compare the speed of a Rust-based nameserver lookup to dig

Three things are tested:

• The speed of the dns_lookup crate in Rust. Nothing magic or custom here.
• The speed of a custom Rust implementation of a nameserver lookup. This was made by me and might not follow spec (didn't really try) and doesn't seem to be as fast as the dns_lookup crate, which uses C bindings. The old adage of "don't reinvent the wheel" rings true.
• The speed of the dig command on a Linux machine. This is a common tool for looking up nameservers. If run on Windows, it uses nslookup instead. nslookup seems to be much slower than dig.

Note

Results are highly dependent on the machine and network conditions. Below, you'll find the results a GitHub Actions runner produced.

Average time over 100 iterations of looking up NS records for mackenly.com:

Rust lib code:
- Average elapsed time: 942.578µs
- Median elapsed time: 236.372µs
- Fastest elapsed time: 230.671µs
- Slowest elapsed time: 70.478818ms

Custom Rust code:
- Average elapsed time: 1.741382ms
- Median elapsed time: 1.220411ms
- Fastest elapsed time: 800.206µs
- Slowest elapsed time: 43.552053ms

Dig command:
- Average elapsed time: 20.203915ms
- Median elapsed time: 18.897586ms
- Fastest elapsed time: 8.512917ms
- Slowest elapsed time: 205.800407ms

The crate returns IP addresses, while the custom code returns the domain names of the nameservers. These are not directly comparable. For my purposes the domain names are more useful. See #4 for more info.

If anyone else goes on this journey, I'd suggest checking out the following resources:

• dns_lookup crate
• The TCP/IP Guide
• Cloudflare's Docs on DNS Wireformat
• This Blog Post
• RFC 1035